This invention relates to a connector used for electrically connecting a pair of terminals.
A conventional connector of this kind includes, for example, a connector shown in FIG. 1 (Japanese Utility Model Laid Open Publication No. 1-103184).
FIG. 1 shows a sectional view of a connector for housing terminals normally provided therein, the terminals being omitted for the sake of clarity. The connector is provided with a female housing 1 and a male housing 3 other. The female housing 1 has a fitting hood 5 with a engaging portion 7 at an edge thereof. The male housing 3 has an elastic lock arm 11 with a lock projection 9. When the male and female housings 1, 3 are fitted together as shown in FIG. 1, the lock projection 9 engages the engaging portion 7 to lock the male and female housings 1, 3 together. In this connector, the lock arm 9 has a sliding face 13 inclined in an inserting direction on a front side of the male housing 3, and forms a triangle in a section thereof.
A lock operation of the elastic lock arm 11 with the lock projection 9 will be described hereinafter with reference to FIG. 2.
When the male and female housing 1, 3 are fitted together, theelastic lock arm 11 moves to the fitting hood 5 in the order shown in FIGS. 2A, 2B and 2C, and finally the lock projection 9 engages the engaging portion 7.
In this operation, first the sliding face 13 of the lock projection 9 comes into contact with the engaging portion 7. Second the sliding face 13 slides on the engaging portion 7 as the male housing 3 is inserted, and when the lock projection 13 moves to a position shown in FIG. 2C, the lock projection 13 is disengaged from the engaging portion 7 to lock the fitted condition. At that moment, the elastic lock arm 11 collides with the engaging portion 7 to produce a clicking sound, so that an operator can confirm the full-fitting condition.
In addition, the inserting force during the fitting of the male housing 3 is shown in FIG. 3 with relation to a stroke of insertion. In FIG. 3, the references (a), (b) and (c) correspond to FIGS. 2A, 2B and 2C respectively. In FIG. 3, suppose that the condition shown in FIG. 2A is at stroke zero (0), and the stroke is increased as shown in FIG. 2B and FIG. 2C, because the flexure of the elastic lock arm 11 increases with the inclination of the sliding face 13. The inserting force gradually increases with the advance of the elastic lock arm 11 shown in FIGS. 2A, 2B and 2C, and the inserting force rapidly becomes zero (0) when the lock projection 9 is locked to the engaging portion 7.
Since the inserting force changes as shown in FIG. 3 in the connector with a lock projection 9 the section of which is triangular, the inserting force even before the condition shown in FIG. 2C is considerably large. Therefore, there is a fear that an operator decides that the connector is in a completely fitted condition due to the increase in the inserting force and stop the insertion of the male housing 3 thereby bringing about an incomplete fitting.
In order to settle the above-described problem, there is a connector having an elastic lock arm 11 with a lock projection 15 shown in FIG. 4 (Japanese Utility Model Laid Open Publication No. 62-76482). This lock projection 15 is provided with a raised sliding face 17 substantially parallel to the extending direction of the elastic lock arm 11 extending in the inserting direction of the male housing 3 and with a initial sliding face 19 disposed on the front side of the raised sliding face 17. Consequently, in this connector, the locking operation of the elastic lock arm 11 is executed as shown in FIGS. 5A through 5F as the insertion of the male housing 3 advances.
First, the initial slide face 19 comes in contact with the engaging portion 7 by the insertion of the male housing 3, so that the engaging lock arm 11 starts to bend. In the condition shown in FIG. 5A in which a front end 17a of the raised sliding face 17 depressed by the engaging portion 7, the elastic lock arm 11 forms the maximum bending angle .theta. with the inserting direction. In this condition, the rear end 17b of the raised slide face 17 forms the maximum height H with the engaging portion 7. The maximum height H is maintained until the instant the front end 17a of the raised sliding face 17 is disengaged from the engaging portion 7 to the lock side. Next, the raised sliding face 17 slides down the engaging portion as shown in FIG. 5C, and the rear end 17b of the raised sliding face 17 slides on the engaging portion 7 as shown in FIG. 5D and 5E. During this movement of the rear end 17b as shown in FIG. 5B through FIG. 5E, the bending angle of the elastic lock arm 11 is gradually decreased from the maximum bending angle .theta.. When the rear end 17b of the raised slide face 17 is disengaged from the engaging portion to the lock side, the lock projection 15 is locked to the engaging portion 7 as shown in FIG. 5F.
The relationship between the stroke of the movement of the elastic lock arm 11 and the magnitude of the inserting force is shown in FIG. 6. The marks of reference (a) through (f) in FIG. 6 correspond to FIGS. 5A through 5F. In the condition shown in FIG. 5A, because the elastic lock arm 11 is bent at the maximum bending angle .theta., the inserting force indicates the maximum value as shown in FIG. 6. When the lock projection 15 moves slightly away from this condition, the inserting force is decreased as shown to (a)' in FIG. 6, and then the value of the inserting force is maintained at a constant value to (b). After that, the value of the inserting force is gradually decreased as shown in sequential order to (c), (d), (e) and indicates zero (0) at (f).
In this manner, in the conventional connector, the inserting force indicates a maximum value (a) at an initial time and then passes through a constant condition and a decreasing condition to reach a locked condition. Therefore, this connector is called an inertia lock type. That is, an operator is required to provide a certain degree of an inserting force at an initial time in the inserting operation, but after that time because the inserting force is rapidly decreasing, the operator can insert the male housing 3 into the female housing 1 without stopping (by inertia). Consequently, there is an advantage that it is possible to prevent an incompletely fitting condition in comparison with the connector shown in FIG. 3.
However, in this inertia lock type, the inserting force is gradually decreased with the advance of the stroke from (b) to (e) as shown in FIG. 6. For this reason, at the time that the lock projection 15 disengaged from the engaging portion 7 to reach the locked condition as shown by (f), the collision force between the elastic lock arm 11 and the engaging portion 7 becomes small, so that the click sounds becomes small. Thus, there has been a problem that an operator cannot auditorily recognize the completely fitted condition.